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For the case of an alloy whose constituents have different valencies, we have = where w i represents the mass fraction of the i th element. In the more complicated case of a variable electric current, the total charge Q is the electric current I ( τ ) integrated over time τ :
Since metals can display multiple oxidation numbers, the exact definition of how many "valence electrons" an element should have in elemental form is somewhat arbitrary, but the following table lists the free electron densities given in Ashcroft and Mermin, which were calculated using the formula above based on reasonable assumptions about ...
The delta function for each charge q i in the sum, δ(r − r i), ensures the integral of charge density over R returns the total charge in R: = = = = = = If all charge carriers have the same charge q (for electrons q = − e , the electron charge ) the charge density can be expressed through the number of charge carriers per unit volume, n ( r ...
The Mulliken population assigns an electronic charge to a given atom A, known as the gross atom population: as the sum of over all orbitals belonging to atom A. The charge, Q A {\displaystyle \mathbf {Q_{A}} } , is then defined as the difference between the number of electrons on the isolated free atom, which is the atomic number Z A ...
In that case, the charge of an ion could be written as =. The charge number in chemistry normally relates to an electric charge. This is a property of specific subatomic atoms. These elements define the electromagnetic contact between the two elements. A chemical charge can be found by using the periodic table.
The −1 occurs because each carbon is bonded to one hydrogen atom (a less electronegative element), and the − 1 / 5 because the total ionic charge of −1 is divided among five equivalent carbons. Again this can be described as a resonance hybrid of five equivalent structures, each having four carbons with oxidation state −1 and ...
For ions, the charge on a particular atom may be denoted with a right-hand superscript. For example, Na +, or Cu 2+. The total charge on a charged molecule or a polyatomic ion may also be shown in this way, such as for hydronium, H 3 O +, or sulfate, SO 2− 4. Here + and − are used in place of +1 and −1, respectively.
When charged particles move in electric and magnetic fields the following two laws apply: Lorentz force law: = (+),; Newton's second law of motion: = =; where F is the force applied to the ion, m is the mass of the particle, a is the acceleration, Q is the electric charge, E is the electric field, and v × B is the cross product of the ion's velocity and the magnetic flux density.